1. Field of the Invention
This invention relates to a brake shoe assembly, more particularly to a brake shoe assembly for a bicycle brake device.
2. Description of the Related Art
Referring to FIG. 1, a conventional brake shoe assembly for a bicycle brake device is shown to comprise a brake shoe 1, a hollow rectangular connecting seat 2, a spring member 3 and two rivets 4. The brake shoe 1 includes a brake pad 101 and a hollow rectangular mounting seat 102. The mounting seat 102 is inverted U-shaped in cross section and is formed of a top wall 103 to which the brake pad 101 is connected and two side walls 104 depending from the top wall 103 of the mounting seat 102. The top wall 103 and the side walls 104 of the mounting seat 102 cooperatively define a cavity 105. The connecting seat 2 is received in the cavity 105 of the mounting seat 102. The connecting seat 2 is U-shaped in cross section and the bottom wall 201 thereof is connected to a shaft projection 202, as shown in FIG. 2. Two opposite side walls 203 of the connecting seat 2 have two pairs of guiding slots 204 formed therein. Each of the pairs of guiding slots 204 are aligned transversely with one another, as best illustrated in FIG. 1. Each of the guiding slots 204 has an upwardly inclined lower section 2041 and a linear section which extends in the direction from a first end 206 of the connecting seat 2 to an opposite second end 207 of the connecting seat 2. Each of the upwardly inclined lower sections 2041 has a lowest end 2043 and an uppermost end 2044. Each of the linear sections 2042 of the guiding slots 204 is connected to the uppermost end of a corresponding one of the upwardly inclined lower sections 2041 of the guiding slots 204.
The two rivets 4 pass respectively through the two pairs of holes 106 (only two holes are shown in a side wall 104) of the side walls 104 of the mounting seat 102 and the two pairs of guiding slots 204 and are fixed to the side walls 104 of the mounting seat 102. The connecting seat 2 has a length which is smaller than that of the mounting seat 102. Therefore, the spring member 3 may be disposed between the first end 206 of the connecting seat 2 and the end 107 of the mounting seat 102 in order to urge the connecting seat to move away from the end 107 of the mounting seat 102 to cause the rivets 4 to abut the lowest ends 2043 of the guiding slots 204, as best illustrated in FIG. 2.
The shaft projection 202 of the connecting seat 2 of the conventional brake shoe assembly is adapted to extend through a bolt 5 which is connected to a brake arm 6 of a bicycle brake device, as best illustrated in FIG. 3. The structure and operations of the bicycle brake device are well known to those skilled in the art. When the bicycle brake device is operated, the pair of brake arms 6 are rotated about the respective pivots 7 to bring the opposed brake shoes 1 of two conventional brake shoe assemblies into contact with opposite sides of the rims 8 of the wheel 9 to exert a braking force. At this time, the connecting seats 2 will be pulled toward the ends 107 of the mounting seats 102 when the rivets 4 are moved along the guiding slots 204 from the lowest end 2043 to the dead end of the linear sections 2042 against the biasing force of the spring members 3. It has been found that the above described conventional brake shoe assembly may provide a larger instantaneous braking force. However, if the rider applies an excessive force to the bicycle brake device, an excessive braking force will be exerted on the wheel of the bicycle, thereby causing the wheel to be locked. When the wheel of the bicycle is locked suddenly by the brake shoe assembly of the conventional bicycle brake device, the wheel will begin to slide and the rider may lose his/her balance and fall down to the ground, thus resulting in injuries.